<!doctype html> 
<html> 
<head> 
    <meta charset="utf-8"> 
    <title></title> 
</head>
<body>
<script type="text/javascript">
	var a = [1,2,3];
	var b = a,c = b;
	//a,b,c   [1,2,3]
	//
	c.push(b);
	//[1,2,3,[1,2,3]]
	//console.log(c);
	b.pop();
	alert(a);//[1,2,3]
	alert(b);//[1,2,3]
	alert(c);//[1,2,3]
</script>
</body>
</html>